Global Space-based Inter-calibration System (GSICS) 4 th WCRP Observations and Assimilation Panel (WOAP) Meeting Barbara J. Ryan Director, WMO Space Programme 30 March 2010 Hamburg

Motivation Applications require well-calibrated and inter-calibrated measurements –Radiance Assimilation in Numerical Weather Prediction –Data Fusion –Climate Data Records Expanding Global Observing System (GOS) Inter-calibration of instruments achieves comparability of measurements from different instruments

Global Space-based Inter-Calibration System (GSICS) To enhance and sustain calibration and validation of satellite observations To intercalibrate critical components of the Global Observing System (GOS) – to climate quality benchmark observations and/or reference sites To provide corrected observations and/or correction algorithms to the user community for current and historical data GSICS Implementation Plan and Programme formally endorsed at CGMS-34 (Nov. 2006)

Actions Quantify the differences – magnitude and uncertainty Correct the differences – physical basis and empirical removal Diagnose the differences – root cause analysis

Space-based Component of WMO’s Global Observing System (GOS) Intercalibration of instruments for comparability of measurements from different instruments

POLAR- POLAR intercalibration Images: NOAA/NESDIS To ensure consistency of datasets from different missions and operators Implementation Plan adopted Nov Organizations currently contributing (+WMO) GEO versus Polar-orbiting Simultaneous Nadir Overpass (SNO) inter-calibration method Global Space-based Inter-calibration System (GSICS)

7 Satellite Biases in NWP After McNally, Bell, et al. ECMWF, 2005 & 2009 Understand the origin of the bias and ideally correct instrument / RT / NWP model at source In principle do not want to apply a correction to unbiased satellite data if it is the NWP model which is biased. Doing so is likely to: –Re-enforce the model bias and degrade the analysis fit to other observations –Produce a biased analysis (bad for re-analysis / climate applications) More accurate satellite observations will facilitate discovery of model errors and their correction. Additional gains in forecast accuracy can be expected SSMIS calibration biases indicate regional weather patterns

ERAIM - JRA-25 ECMWF - JRA-25 Difference between JRA-25 vs ECMWF and JRA-25 vs ERA Interim (column water vapor above 500 mb) ECMWF Weather analysis and reanalysis different because the ECMWF bias-tuning changed in According to Tony McNally, ECMWF will turn off bias-tuning of AIRS water vapor channels to correct the problem. Larger differences with ERAIM (13%) vs ECMWF WX analysis (1%)

Before Intercalibraion After Intercalibration Calibration uncertainties translate to uncertainties in climate change detection. Trend of global oceanic total precipitable water decreases from 0.54 mm/decade to 0.34 mm/decade after intercalibration. Calibration is Critical for Climate Change Detection

Organizations contributing to GSICS NOAA NASA NIST EUMETSAT CNES CMA JMA KMA WMO Observers: JAXA ESA Current focus is on the intercalibration of operational satellites, and makes use of key research instruments like AIRS and MODIS as reference instruments CEOS Precipitation Constellation is working with GSICS via GPM X-Cal Working Group

CSS GPRC CSS GSICS Executive Panel GRWGGDWG GPRC GCC CSS Calibration Support Segments (reference sites, benchmark measuremen ts, aircraft, model simulations) Coordination Center Regional Processing Research Centers at Satellite Agencies GSICS Structure Research working group - Consensus algorithms Data working group - Formats, Servers

Current Workplan Interagency collaboration on algorithms (GRWG) and data exchange and formats (GDWG) Product acceptance and documentation requirements, metadata standards, data formats, website standards Routine intercalibration (monitor and correct) all operational GEO Infrared imagers using IASI and AIRS –MODIS and Deep Convective Clouds for visible channels Intercalibration of LEO instruments –HIRS, SSMI, AMSU, MHS, AVHRR, AIRS, IASI, FY3, –GOME-2, OMI, SBUV Traceability –Campaigns –Key collocation datasets –Requirements for pre-launch calibration Root causes and corrections

Best Practice Guidelines for Pre-Launch Characterization and Calibration of Instruments for Optical Remote Sensing GSICS Guideline Document

Ch6 Ch4 Ch3 Ch2 IASI AIRS First international coordinated GSICS project is the intercalibration of geostationary infrared channels with IASI and AIRS Web Accessible

GSICS Correction Algorithm for Geostationary Infrared Imagers GSICS will provide correction coefficients for all GEOs from 2003 (beginning of AIRS record) to present The first major deliverable to the user community is the GSICS correction algorithm for geostationary satellites. The user applies the correction to the original data using GSICS provided software and coefficients. The correction adjusts the GOES data to be consistent with IASI and AIRS. The figures to the left show the difference between observed and calculated brightness temperatures (from NCEP analysis) before and after correction The bias is reduced from 3 K to nearly zero Before 3K Bias After: ~ 0K Bias

Web-based Monitoring MTSAT- AIRS/IASI Monitoring Example from JMA website MTSAT-1R – AIRS/IASI Time Series of Bias –at 220, 250, 290K

Monitoring GOES12-AIRS at NOAA

Monitoring Meteosat9-IASI Time series of brightness temperature differences between MSG2-IASI for typical clear-sky radiances. Error bars represent statistical uncertainty on each mean bias (may be very small). IR3.9-IR12.0: Small, stable Biases <0.2K ± 0.05K IR13.4: Larger Bias ~-1K -0.05K/mnth+Jump

GSICS Correction available for MSG EUMETSAT routinely runs prototype inter- calibration of MSG- IASI Results published on webpage for Inter- calibration Services : – t.int/Home/Main/Acc ess_to_Data/Intercal ibrationServiceshttp:// t.int/Home/Main/Acc ess_to_Data/Intercal ibrationServices Webpage also allows access to coefficients required to apply GSICS Correction Users can implement this as change in calibration coefficients

User Community Engagement Meeting 9/09 –Satellite Community – generation of CDRs SCOPE-CM ISCCP National programs - SDS, SAFs, –Satellite Community - NWP direct radiance assimilation –Reanalysis Community Next reanalysis – GSICS first major deliverable - intercalibrated geostationary data using IASI/AIRS from 2003 – –Satellite Acquisition Programs Prelaunch instrument characterization guidelines Cal/Val Plans User feedback: Geostationary intercalibration, Microwave Intercalibration

GSICS Outcomes Coordinated international intersatellite calibration program Exchange of critical datasets for cal/val Best practices/requirements for monitoring observing system performance (with CEOS WGCV) Best practices/requirements for prelaunch characterization (with CEOS WGCV) Establish requirements for cal/val (with CEOS WGCV) Advocate for benchmark systems Quarterly reports of observing system performance and recommended solutions Improved sensor characterization High quality radiances for weather, climate & environmental applications